This collaborative project has established an animal model of HTLV-I associated disease in non-human primates with a primary HTLV-I viral isolate, derived from a human patient with HTLV-I associated tropical spastic paraparesis (TSP). Two of three inoculated rhesus macaques were infected and showed signs of disease. One animal presented with a findings identical to that in the original patient, with muscle atrophy, polymyositis, and arthritis . The second animal was dually infected with SIV and developed signs suggestive of smoldering HTLV-I induced leukemia in the presence of SIV immunodeficiency disease. This work is published. Five additional animals were inoculated with this same HTLV-I isolate. Four of five had persistent viral antigen detection in the peripheral circulation associated with weak humoral responses, while the fifth animal was persistently antigen negative associated with a strong humoral response. These results suggest that immune responses are important in controlling HTLV-I virus expression in the macaque model. This work was presented at a national conference and the abstract published. We are currently in the process of developing autologous transformed cell lines from each of the animals as well as and vaccinia-HTLV-I virus constructs to characterize the